What are the documentation requirements for code 51798?

What are the documentation requirements for code 51798? Is documenting the residual amount enough, or do we have to have the printout from the bladder scan? Some of the machines do not have the capability to print out the scan. We have been requesting that medical assistants scan the printout but would like to know if entering the postvoid residual is enough.

Code 51798 reads: Measurement of post-voiding residual urine and/or bladder capacity by ultrasound, non-imaging.

As such, the code is not treated the same as other ultrasound codes with regard to documentation requirements. Documentation should include the reason the postvoid residual (PVR) was obtained that day, the postvoid amount, should indicate that ultrasound was used and how it was used in medical decision-making. Documentation of how PVR is used in medical decision-making can be explicit or implicit in the documentation for the visit and is not required to be documented in the same place as the postvoid amount and reason for PVR.